Event-related P300 potentials are closely reflecting cognitive functions such as stimulus evaluation time (P300 latency) and task relevance (P300 amplitude). Hence, both their potential clinical application for detecting slight cognitive disturbances and an increasing interest in the aging of cognitive human brain functions resulted in a growing number of studies on age-related P300 changes. Although there are converging lines of evidence that aging results in prolongations of P300 latencies, reductions of P300 amplitudes and a more equipotential P300 scalp distribution, the amount of these changes and the best fit for the P300-age interactions, respectively, remain still controversial. In general, these P300 alterations obviously reflect only minor cognitive changes during normal aging. For their clinical application, however, it is necessary to obtain an age-matched normative database. Furthermore, the increased P300 variability in the elderly has to be reduced--as far as possible--by appropriate simple P300 paradigms which should be preferentially applied in longitudinal analyses to differentiate normal from pathological aging of cognitive functions. Finally, additional cross-correlational analyses between the P300 and morphological as well as neurobiochemical data are needed. By these means, our knowledge about age-related changes of cognitive brain functions should be considerably enlarged.